Flexible liner hanger

ABSTRACT

A gas turbine engine exhaust system includes a liner extending along an axial direction and a radial direction and circumscribing a combustion plenum, a high pressure plenum circumscribing the liner along the radial direction, a structural component circumscribing the high pressure plenum along the radial direction, and a leaf spring fastener arranged within the high pressure plenum. The leaf spring fastener is arranged between the liner and the structural component.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. provisional application Ser. No. 61/764,782, entitled “FLEXIBLE LINER HANGER,” filed Feb. 14, 2013 by Dale William Petty. U.S. provisional application Ser. No. 61/764,782 is incorporated by reference herein.

BACKGROUND

Hangers or spacing fasteners are used in a variety of applications in which two components are to be kept at a specified distance from each other. In gas turbine engines, such hangers are used, for example, to hold exhaust liners at a desired distance from a duct. During operation of a gas turbine engine, the exhaust liner is subjected to a range of extreme temperatures and pressures, and separates a hot exhaust flowpath from a relatively colder cooling air flow.

Often, an exhaust liner is annularly shaped and is surrounded by a cooling air duct. The cooling air duct may be filled with a pressurized cooling gas, which is admitted to the exhaust flow for a variety of purposes, such as diluting or modifying the flowpath of combustion or exhaust gases, or effusion cooling of the exhaust liner and other components.

SUMMARY

A gas turbine engine exhaust system has a liner extending along an axial direction and a radial direction and circumscribing a combustion plenum. A high pressure plenum circumscribes the liner along the radial direction. A structural component circumscribes the high pressure plenum along the radial direction. At least one leaf spring fastener is arranged within the high pressure plenum between the liner and the structural component.

A fastener includes a spring having a first end and a second end, the spring having a spring constant profile; a first connector at the first end of the spring to connect the spring to a combustor liner; and a second connector at the second end of the spring to connect the spring to a structural component of a gas turbine engine exhaust.

A method of attaching a liner to a structural component in a gas turbine engine exhaust system includes arranging a liner radially within a structural component, the liner and the structural component separated by a high pressure plenum; attaching a spring fastener to the liner at a first end of the spring; and attaching the spring fastener to the structural component at a second end of the spring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic of a gas turbine engine.

FIG. 2A is a cross-sectional view of the gas turbine engine of FIG. 1 taken along line 2-2.

FIG. 2B is a cross-sectional view of the gas turbine engine of FIG. 1, taken along line 2-2, showing deflection of the duct.

FIG. 3 is a partially exploded perspective view of a flexible hanger liner.

FIG. 4 is a perspective view of a dampened, multi-leaf spring flexible hanger.

FIG. 5 is a perspective view of a flexible hanger liner including a travel limited coil spring.

DETAILED DESCRIPTION

FIG. 1 is a simplified schematic of gas turbine engine 10. Gas turbine engine 10 includes gas turbine 12 and exhaust system 14. Gas turbine 12 and exhaust system 14 are arranged along axis 16, and are connected at intersection 18. Gas turbine 12 includes inlet 20. Exhaust system 14 includes exhaust nozzle 22 and exhaust outlet 24.

Gas turbine engine 10 may be any type of Brayton-type engine, such as a turbofan, turbojet, or turboprop engine. Gas turbine engine 10 may be used for commercial power generation, or it may be used in aviation, among other uses.

Gas turbine 12 includes inlet 20, and is capable of taking in, compressing, and combusting air and fuel for use in gas turbine engine 10. Gas turbine 12 may include any of a variety of components, such as fan sections, low pressure compressor and high pressure compressor sections, a combustor section, and high pressure and low pressure turbine sections, to facilitate combustion and power/thrust generation.

Exhaust system 14 is an engine section from which exhaust is expelled. Exhaust system 14 includes exhaust nozzle 22, which is a region in which exhaust gases are relatively restricted. Exhaust system 14 also includes exhaust outlet 24, through which exhaust gases escape.

Gas turbine 12 and exhaust system 14 are connected at intersection 18. Gas turbine 12 and exhaust system 14 are in fluid communication. Thus, air may enter gas turbine engine 10 through inlet 20, be compressed in gas turbine 12, pass through intersection 18 to exhaust system 14 where it is combusted with fuel (not shown), flow through exhaust nozzle 22 and exit gas turbine engine 10 via exhaust outlet 24. Intersection 18 may be, for example, interlocking flange sections holding gas turbine 12 to exhaust system 14.

FIG. 2A is a cross-sectional view of gas turbine engine 10 taken through exhaust system 14 along line 2-2. FIG. 2A shows centerline 16 as described in FIG. 1, as well as liner 30, duct 32, hangers 34, cooling fluid C, and combustion gas H.

Liner 30 is an exhaust liner. Liner 30 is made from a material capable of withstanding contact with fluids at high temperature, pressure, and/or velocity. For example, liner 30 may be made of a high-temperature superalloy, and may include features such as effusion holes or diffusion holes (not shown). Liner 30 is shaped as an elliptical annulus. In other embodiments, liner 30 may be a cylindrical annulus or other shape. Liner 30 surrounds a combustion plenum through which combustion gas H can flow.

Duct 32 is a structural component of a gas turbine engine. Duct 32 is often made from a gas-impermeable material capable of withstanding high pressure gradients, such as metals, polymers, or carbon fiber. As with liner 30, duct 32 is an elliptical annulus, but in alternative embodiments may have alternative geometries. Duct 32 is often considerably stiffer than liner 30, because a stiff liner 30 would generally have high stresses due to thermal gradients across the thickness of its structure. Duct 32 surrounds a high pressure plenum through which cooling fluid C can flow. Liner 30 is attached to duct 32 with a plurality of hangers 34 that run through the high pressure plenum.

Hangers 34 are leaf spring hangers capable of holding two spaced components at a desired distance from each other. Hangers 34 have a desired elasticity such that spaced components connected by hangers 34 may move relatively closer or farther from each other depending on the force used to compress or divide them. Hangers 34 pivot and/or slide to accommodate relative thermal movement between liner 30 and duct 32. The flexibility of hanger 34 prevents duct 32 from pulling liner 30 out of shape when the plenum defined by duct 32 is pressurized.

Cooling fluid C is a fluid such as compressed air from gas turbine 12 (FIG. 1). Exhaust gas H is a fluid that has undergone combustion in exhaust system 14. Cooling fluid C is relatively cooler and higher pressure than exhaust gas H.

Liner 30 contains exhaust gas H in the combustion plenum as it moves towards exhaust outlet 24 (FIG. 1). Liner 30 may be partially porous, so as to admit cooling fluid C into exhaust gas H. Cooling fluid C is contained by duct 32 in the high pressure plenum. Liner 30 may be a thin structure attached with a plurality of hangers 34 to duct 32.

FIG. 2A shows a cross-section of exhaust system 14 when it is not under load. Loads may be applied on liner 30 and/or duct 32 depending on the pressure of cooling fluid C and exhaust gas H. Liner 30 may be subject to loading from relative motion to duct 32 due to thermal expansion or contraction from contact with exhaust gas H and/or cooling fluid C.

As shown in FIG. 2A, liner 30 is tuned to a specific shape. By increasing or decreasing the relative densities of hangers 34 connecting liner 30 to duct 32, a desired load distribution in the radially outward direction is applied. Such load distribution may be tuned to pull liner 30 outward more forcefully in some areas than others. This may be useful in generating a specific gas flowpath for exhaust gas H and/or cooling fluid C.

FIG. 2B shows the same cross-section of exhaust system 14 of FIG. 1 along line 2-2 that was shown in FIG. 2A, except that duct 32 has been deformed. As previously described, such deformation may occur where duct 32 is made of a flexible and/or elastic material, and cooling fluid C is pressurized. Due to the width and operating pressures of some non-round exhaust systems, metal ducts (steels, nickel alloys, titanium alloys) or high strength composites deflect enough to effect exhaust nozzle performance if the liner is rigidly hung to the duct. Flexible hangers 34 prevent duct 32 from pulling liner 30 out of a desired shape when the plenum defined by liner 30 and duct 32 is pressurized. As shown in FIG. 2B, duct 32 has been deformed radially outward, away from axis 16. Duct 32 is limited in its outward deflection by hangers 34, which have extended to be almost straight. Notably, due to elasticity of hangers 34, liner 30 remains in its original shape and position with respect to axis 16, despite deformation of duct 32.

Non-round jet engine exhaust systems deflect under normal operation due to pressure and temperature changes. If liner 30 is rigidly attached to duct 32, liner 30 will be pressure deflected along with duct 32 and likely to distort the flowpath of surface profile. In some areas of the exhaust system (such as exhaust throat 22, FIG. 1), it is important to maintain the flowpath surface profile.

Elasticity of hangers 34 allows for greater design freedom in associated liner 30 and/or duct 34. Exhaust gas H may reach temperatures in excess of 650° C. As a result, thermal expansion of liner 30 may occur. Where liner 30 is supported by hangers 34 having elasticity, such thermal expansion is possible, even where liner 30 has a complex shape. Additionally, elastic hangers 34 may permit a less stiff, lighter or smaller exhaust static structure.

FIG. 3 is a partially exploded view showing hanger 34 of FIGS. 2A-2B. Hanger 34 includes first bracket 40, second bracket 42, connectors 44, leaf spring portion 46, and pins 48. First bracket 40 and second bracket 42 include drill holes 50 and pin holes 52.

First bracket 40 and second bracket 42 are fasteners used to connect hanger 34 to liner 30 and/or duct 32 (FIGS. 2A-2B). As shown in FIG. 3, first bracket 40 and second bracket 42 are plates having drill holes 50 in order to facilitate connection to an adjacent component, such as liner 30 and/or duct 32 (FIGS. 2A-2B).

Connectors 44 are hollow annular structures connecting first bracket 40 and second bracket 42 to leaf spring portion 46. Leaf portion 46 has a curvature, thickness, and composition in order to produce a desired spring constant. Leaf spring portion 46 may be integrally formed with connectors 44, or may be capable of fastening to connectors 44. Each of pins 48 passes through both one of connectors 44 and one of pin holes 52. In some embodiments, first bracket 40 and second bracket 42 are connected to leaf spring portion in such a way that leaf portion 46 may pivot with respect to first bracket 40, second bracket 42, or both.

First bracket 40 is connected to one of connectors 44 by one of pins 48 passing through connector 44 and pin hole 52. Pin 48 may be secured by any of a variety of means, including welding, brazing, swaging, riveting, adhesives, a cotter pin, or other fasteners known by those skilled in the art. Connector 44 is attached to leaf spring portion 46, either by welding brazing, or by being integrally formed with leaf spring portion 46, among other fasteners known by those skilled in the art. Similarly, second bracket 42 is connected to the other of connectors 44 by the other of pins 48 passing through connector 44 and pin hole 52.

Hanger 34 has a desired spring constant, set by the curvature, thickness, and composition of leaf spring portion 46. Thus, hanger 34 is uniquely useful to separate components which optimally have the ability to deflect under applied force. Hanger 34 allows limited deflection, such that the exhaust liner flowpath profile could be maintained despite pressure deflection of duct 32.

As described with respect to the preceding figures, hanger 34 separates an exhaust liner from a duct. However, in alternative embodiments, hanger 34 may be used to separate any two components which are separated from one another and optimally have the ability to deflect under applied force.

FIG. 4 is a perspective view of dampened hanger 134. Dampened hanger 134 includes connectors 144. Dampened hanger 134 includes primary leaf spring 146A, secondary leaf spring 146B, and tabs 146C.

Connectors 144 differ from hangers 44 in that they are a single rolled or formed piece capable of connecting to a compatible structure such as a pin (not shown). Connectors 144 are integrally formed with primary leaf spring 146A.

Primary leaf spring 146A is similar to leaf spring 46 (FIG. 3) in that it has a curvature, thickness, and composition in order to produce a desired spring constant. Primary leaf spring 146A is integrally formed with connectors 144. Primary leaf spring 146A may have a resonant frequency, such that without dampening primary leaf spring 146A could be induced to form a standing wave.

Secondary leaf spring 146B is also a leaf spring-like object, with a curvature, thickness, and composition configured to produce a desired spring constant. Secondary leaf spring 146B may have a resonant frequency, but if so the resonant frequency is tuned to avoid constructively interfering with standing waves in primary leaf spring 146A. In some embodiments, secondary leaf spring 146B may be configured to cause destructive interference with standing waves in primary leaf spring 146A.

Tabs 146C are integrally formed with secondary leaf spring 146B. Tabs 146C are capable of connecting primary leaf spring 146A to secondary leaf spring 146B.

Primary leaf spring 146A is arranged adjacent to secondary leaf spring 146B. Each of primary leaf spring 146A and secondary leaf spring 146B has a spring constant determined by its dimensions and composition. Primary leaf spring 146A is bound to secondary leaf spring 146B by tabs 146C. The combined structure may be attached to other components by fasteners 144. For example, tabs 146C may connect secondary leaf spring 146B to primary leaf spring 146A, and primary leaf spring 146A is shaped to form connectors 144 to attach to liner 30 (FIGS. 2A-2B) and/or duct 32 (FIGS. 2A-2B).

Dampened hanger 134 differs from hangers 34 (FIGS. 2A-2B, 3) in that dampened hanger 134 includes primary leaf spring 146A and secondary leaf spring 146B, whereas hanger 34 (FIGS. 2A-2B, 3) includes only leaf spring 46 (FIG. 3). As a result, dampened hanger 134 is capable of dampening standing vibrations. Incorporation of secondary leaf spring 146B may be used to generate more complex elasticity profiles for each hanger 134.

While FIG. 4 only includes primary leaf spring 146A and secondary leaf spring 146B, other embodiments may include three or even more leaf springs. Such constructions may be useful to create complex elasticity profiles and avoid standing waves that are generally undesirable in gas turbine engine fasteners.

FIG. 5 is a perspective view of spring hanger 234. Spring hanger 234 includes fasteners 244, spring 246, and connectors 254.

Spring 246 is a spring with a spring constant. Spring 246 regulates the relative movement of components attached to spring hanger 234. Fasteners 244 are rods similar to fasteners 44 (FIG. 3). A variety of types of fastener may be used such that fasteners 244 are capable of attaching spring hanger 234 to adjacent components. Connectors 254 attach spring 246 to fasteners 244.

In the embodiment shown in FIG. 5, travel is limited by the free space between coils of spring 246. In alternative embodiments, relative movement between fasteners 244 may be limited with a stop piece (not shown). Spring 246 may be tuned for a desired optimal stiffness.

As the embodiment of spring hanger 234 in FIG. 5 shows, the concept of a spring hanger is not limited to leaf springs. Coil spring hanger guides can provide light interference to dampen natural frequencies in the coils.

Possible Embodiments

The following are non-exclusive descriptions of possible embodiments of the present invention.

A gas turbine engine exhaust system includes a liner extending along an axial direction and a radial direction and circumscribing a combustion plenum, a high pressure plenum circumscribing the liner along the radial direction, a structural component circumscribing the high pressure plenum along the radial direction, and a leaf spring fastener arranged within the high pressure plenum between the liner and the structural component.

The gas turbine engine exhaust system of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components.

The exhaust system may include a plurality of leaf spring fasteners. The leaf spring fastener may include: a spring body portion, a first connector attached to the liner, and a second connector attached to the structural component. The spring body portion has a spring constant profile. The first connector and the second connector may include: a plate affixed to the liner, the plate including a protrusion, and a rod passing through the protrusion and a portion of the spring body portion. The structural component may extend a radial amount determined by a pressure of a fluid within the high pressure plenum.

A fastener includes a leaf spring having a first end and a second end, a first connector at the first end of the leaf spring to connect the leaf spring to an exhaust liner, and a second connector at the second end of the leaf spring to connect the leaf spring to a structural component of a gas turbine engine exhaust.

The fastener of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations, and/or additional components.

The gas turbine engine may be non-cylindrical. For example, the gas turbine engine may be substantially shaped as an elliptical cylinder. There may be a high-pressure plenum between the liner and the structural component. A high-pressure air mass may be located in the high pressure plenum. The first connector may include a plate affixed to the liner, the plate including a protrusion, a rod passing through the protrusion and a portion of the leaf spring. The plate may be affixed to the liner by a weld joint or by a rivet. The leaf spring may have a spring constant profile.

A method of attaching a liner to a structural component in a gas turbine engine exhaust system includes: arranging a liner radially within a structural component, the liner and the structural component separated by a high pressure plenum; attaching a leaf spring fastener to the liner at a first end of the leaf spring; attaching the leaf spring fastener to the structural component at a second end of the leaf spring.

The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, steps, and/or additional components.

The method may further include filling the high pressure plenum with a pressurized working fluid. Filling the high pressure plenum may cause the structural component to deflect radially outwards. Radial deflection of the structural component may cause the leaf springs to elongate. A plurality of leaf spring fasteners may be attached to the liner and to the structural component.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. 

1. A gas turbine engine exhaust system, the system comprising: a liner extending along an axial direction and a radial direction and circumscribing a combustion plenum; a high pressure plenum circumscribing the liner along the radial direction; a structural component circumscribing the high pressure plenum along the radial direction; and a spring fastener arranged within the high pressure plenum, the spring fastener connected to the liner and the structural component.
 2. The exhaust system of claim 1, including a plurality of spring fasteners.
 3. The exhaust system of claim 1, wherein the spring fastener includes: a spring body having a spring constant profile; a first connector attached to the liner and the spring body; and a second connector attached to the structural component and the spring body.
 4. The exhaust system of claim 3, wherein the first connector and the second connector are pivotably connected to the spring body.
 5. The exhaust system of claim 3, wherein the first connector and the second connector include: a plate affixed to the liner, the plate including a protrusion; and a rod passing through the protrusion and a portion of the spring body portion.
 6. The exhaust system of claim 3, wherein the structural component extends a radial amount determined by a pressure of a fluid within the high pressure plenum.
 7. A fastener comprising: a spring having a first end and a second end, the spring having a spring constant profile; a first connector at the first end of the spring to connect the spring to a combustor liner; and a second connector at the second end of the spring to connect the spring to a structural component of a gas turbine engine exhaust.
 8. The fastener of claim 7, wherein the gas turbine engine is non-cylindrical.
 9. The fastener of claim 8, wherein the gas turbine engine exhaust is substantially shaped as an elliptical cylinder.
 10. The fastener of claim 7, and further comprising a high-pressure plenum between the liner and the structural component.
 11. The fastener of claim 10, wherein a high-pressure air mass is located in the high pressure plenum.
 12. The fastener of claim 7, wherein the first connector includes: a plate affixed to the liner, the plate including a protrusion; and a rod passing through the protrusion and a portion of the spring.
 13. The fastener of claim 12, wherein the plate is affixed to the liner by a weld joint.
 14. The fastener of claim 12, wherein the plate is affixed to the liner by a rivet.
 15. The fastener of claim 12, wherein the plate is pivotably connected to the spring.
 16. A method of attaching a liner to a structural component in a gas turbine engine exhaust system, the method comprising: arranging a liner radially within a structural component, the liner and the structural component separated by a high pressure plenum; attaching a spring fastener to the liner at a first end of the spring; and attaching the spring fastener to the structural component at a second end of the spring.
 17. The method of claim 16, and further comprising filling the high pressure plenum with a pressurized working fluid.
 18. The method of claim 17, wherein filling the high pressure plenum causes the structural component to deflect radially outwards.
 19. The method of claim 17, wherein radial deflection of the structural component causes the spring to elongate.
 20. The method of claim 16, and further comprising attaching a plurality of spring fasteners to the liner and to the structural component. 